The saddle of a cycle is usually fixed in elevation by mechanically clamping a saddle support attached to the cycle in the upper portion of the rear inclined frame tube of the cycle. The rear inclined frame tube in a bicycle, for example, is also referred to as the seat tube. The saddle or seat clamp of the cycle frame must be loosened in order to adjust the saddle in elevation. The saddle is moved upwardly or downwardly with the saddle support in the rear inclined frame tube and the clamp of the cycle frame is then again tightened. For each of these activities, reaction forces act upon the frame which usually is held by the person making the adjustment generating the forces. This work can mostly only be performed during standstill of the cycle and with hand tools.
The saddle elevation optimal for the operation of a cycle is an elevation different than the saddle elevation needed at standstill. The elevation at standstill of the cycle permits the cyclist to place both feet on the ground without it being necessary to dismount from the saddle.
Because the adjustment of the saddle elevation is associated with the above-mentioned work, the saddle elevation adjusted on each cycle is a compromise between the requirement of the cyclist, on the one hand, to be able to place both feet on the ground at standstill so that the cyclist must not dismount in order to prevent cycle and cyclist from falling over at standstill and, on the other hand, in order to have the saddle so high that the cyclist can extend the legs in an ergonomically advantageous manner to drive the sprocket via the pedals. The ideal adjustment of saddle elevation for standstill is not the ideal adjustment of the saddle elevation for cycle operation and vice versa.
German Patent Publication 2,900,780 discloses an arrangement with which the elevation of the saddle can be adjusted simpler and more rapidly during standstill of the cycle and when the cyclist has dismounted than was possible with the conventional screw/nut clamp up to that time. While the saddle is fixed very precisely and immovable with respect to the cycle frame with the conventional screw/nut clamp, the arrangement of German Patent Publication 2,900,780 permits only the positioning of the unloaded saddle in a zero position in order to move the same up and down with changing load as is usual during normal cycle operating states. The length of the movements about the zero position is dependent upon the gas pressure in the spring and on the forces acting on the saddle in the longitudinal-axial direction of the arrangement. For this purpose, the arrangement includes a gas pressure spring having a pregiven gas pressure for which a blockable connection is provided between the two gas chambers which are located at both ends of the piston. The blockable connection can release or block the volume flow between the two gas chambers when the piston is charged. In this way, the piston can be positioned between the two end positions "completely down" and "completely up". In each position of the piston above "completely down", the air or gas volume is compressible in each position of the piston above "completely down" and acts resiliently on the vertical saddle movements. The spring paths increase for the piston position "completely up" and the saddle becomes softer.
This arrangement includes a minimum construction size which cannot be built into existing cycle frames.
German Patent 651,151 discloses an arrangement wherein the elevation of the cycle saddle is adjustable at standstill and during operation of the cycle. This arrangement includes an adjustable saddle support which is hydraulically charged and for which two pistons, which operate in a cylinder, are under resilient pressure. A valve can be actuated from the saddle by means of a Bowden cable in order to establish equilibrium of the liquid in two pressure chambers. This adjusting arrangement uses a cylindrical helical spring as an energy store and therefore requires a much longer structural space than a touring cycle allows.
This arrangement includes considerable technical shortcomings which make assembly most complicated and requires a long structural length. Furthermore, for this reason, this arrangement was unsuccessful in the marketplace.